docs: def view_num_units(token, dstore):
      """
      Display the number of units by taxonomy
      """
      taxo = dstore['assetcol/tagcol/taxonomy'].value
      counts = collections.Counter()
      for asset in dstore['assetcol']:
          counts[taxo[asset['taxonomy']]] += asset['number']
      data = sorted(counts.items())
      data.append(('*ALL*', sum(d[1] for d in data)))
      return rst_table(data, header=['taxonomy', 'num_units'])